4 . G11 LifeSciences DigitalSupport web Environmental Studies

Study & Master Support Pack | Grade 11 CAPS Life Sciences Environmental studies This support pack for the Environmental studies strand of the Life Sciences Grade 11 CAPS curriculum provides revision summaries on the topic to help prepare for the examinations. Learners can work through these individually at home or these could form the basis of a catch-up class or online lesson. You have permission to print or photocopy this document or distribute it electronically via email or WhatsApp. Cambridge University Press Africa is a proudly South African publisher. For more information on our Study & Master CAPS-approved textbooks and valuable resource materials, visit www.cambridge.org Brighter thinking | Better learning www.cambridge.org

UNIT 1: Population ecology benefits of packs parasitism mutualism herds/flocks (hunting) (avoidance) dominance division of specialisation commensalism tasks (castes) intraspecific primary secondary Social organisation succession succession Interaction in the competition environment Community change interspecific predation over time: succession Population logistic and ecology possible endpoints geometric depending on limiting factors, environmental fluctuations carrying capacity fluctuations Population size Human population reasons for births immigration exponential growth mortality emigration forecasts of SA’s population growth: age and gender consequences for differences of environment different countries

UNIT 1 Population ecology Population size • Population size is determined by birth, death, immigration and emigration. • The size of a population can be counted directly or estimated indirectly using different methods. • There are at least six ecological factors that regulate the size of populations. • The size of a population fluctuates around the carrying capacity of the environment that supports the population. • Species with a long lifespan, limited number of offspring and extensive parental care usually follow a logistic population growth pattern (sigmoid or S-curve). • Species with a short lifespan, large number of offspring and no or limited parental care usually follow a geometric growth pattern (exponential or J-shaped curve). Interactions in the environment • Interactions between members of the same species, and also members of different species, contribute towards maintaining balanced ecosystems. • Predator-prey relationships regulate the size of both predator and prey populations in a cyclic way. • Two specialised forms of competition allow species to share similar resources. These are competitive exclusion and resource partitioning. • Parasitism, mutualism and commensalism are examples of interactions in the environment. Social organisation • Individuals in a community show social organisation, e.g. herds and flocks. Community change over time: succession • Plant and animal communities are not static. They change by going through developmental stages collectively known as ecological succession. The human population • The world’s population is growing at an exponential rate. The global human population size reached 7.8 billion by June 2020. It took 200 000 years of human history to reach the first billion and only 200 years to reach 7 billion. So, strictly speaking, our population is growing faster than the normal exponential rate. • Scientists are of the opinion that the global population will reach 8 billion by 2023, 9 billion by 2048 and 10 billion by 2100. This is alarming if one considers that the world’s natural carrying capacity has already been exceeded. • However, humans have the unique ability, unlike any other species, to overcome density dependent limiting factors by altering the environment to satisfy their own needs and greed. • This humans do by using their mental ability and technical skills. Modern agriculture, technology, sanitation and medical advances have elevated the Earth’s artificial carrying capacity to between 9 to 10 billion. • This comes at the expense of human wellbeing as we have already seen by the world wide increase of economic and social refugees that have already doubled during the last decade.

• As can be seen in Figure 2, the global population growth is optimistically expected to show a slowdown beyond 8 billion when the environmental resistance intensifies as the carrying capacity is reached. • However, it is uncertain whether an equilibrium phase will be reached (logistic S-shaped growth) or whether the population will crash (geometric J-shaped growth). Population of the Earth Number of people living worldwide since 1700 2048 9 bn 9 8 2023 Human population (billions) 2012 8 bn 7 7 bn 6 1999 1987 6 bn 5 5 bn 4 1974 1960 4 bn 3 3 bn 1804 2 1 bn 1927 1 2 bn 0 1700 1800 1900 2000 Year Figure 2 Estimated global human population growth The population of South Africa • The population pyramid in Figure 3 is a most recent estimate of the age and gender distribution of South Africa. 100+ 95–99 South Africa 2017 90–94 85–89 male female 80–84 75–79 Key: 70–74 65–69 postreproductive 60–64 55–59 reproductive Age (in years) 50–54 prereproductive 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 3 2.5 2 2.5 1 0.5 0 0.5 1 1.5 2 2.5 3 Millions Figure 3 Population pyramid of South Africa • South African population is becoming rapidly urbanised and we have an age structure that is skewed towards young people. • South Africa is going through a demographic transition. Death rates are dropping, birth rates are declining and there is a declining rate of natural population increase. • South Africa is still a very youthful nation. This can be seen in the broad base of the population pyramid. • The age group with the largest numbers is those that are currently bearing children or will bear children in the future. This means that a great deal more environmental and economic resources are going to be required in the future to serve all citizens in the country.

• By 2020, South Africa’s human population reached 58.8 million. Ten years ago, the figure was 50 million. With this rapid growth rate, we may be heading for a crises in securing future resources for all. South African population 75 70 60 55 Population in millions 55 50 45 40 35 30 25 20 15 1960 1970 1980 1990 2000 2010 2020 2030 2040 Figure 4 Population growth in South Africa from 1960–2020

UNIT 2: Human impact on the environment effect of mining on water quality thermal droughts and pollution floods diseases, eutrophication, poor farming algal blooms human practices alien exponential quality plants population water use in homes, alien plants growth and reduction industry, agriculture and mining: pollution of agricultural land Water Food security loss of wild wastage varieties: impact on gene pools boreholes and effects on aquifers availability building dams genetically wastage engineered exotic plants foods and depletion of destruction water table of wetlands droughts and poor farming Human floods practices impact habitat destruction on the poaching environment ozone Loss of depletion biodiversity (the sixth alien The extinction) plant methane emissions atmosphere invasion and climate change greenhouse indigenous knowledge effect and systems and sustainable global warming use of the environment carbon dioxide emissions deforestation reduction of carbon footprint Solid waste disposal managing disposal of dump sites for nuclear waste rehabilitation methane from dump sites preventing soil and for domestic use water pollution

UNIT 2 Human impact on the environment The atmosphere and climate change • Carbon dioxide emissions have risen steeply since 1950. • Carbon dioxide is one of the greenhouse gases that contributes to climate change. • The other important greenhouse gases are methane, nitrogen dioxide and water vapour. • The carbon footprint is a unit that can be used to work out the cost, in terms of carbon emissions, of human activities on the environment. • Forests are the largest terrestrial carbon sinks. Deforestation and desertification reduce Earth’s ability to soak up excess carbon dioxide and other greenhouse gases in the atmosphere. • The greenhouse effect is the name given to the fact that the long wavelengths of solar energy are reflected back to Earth as they hit the atmosphere and that carbon dioxide and other greenhouse gases trap some of this long-wave energy. This forms a “blanket” around the Earth that keeps the planet at the correct temperature for life. • Global warming is caused by increasing levels of greenhouse gases, which are causing a rise in the Earth’s temperature, which is causing climate change. • Methane emissions from landfill sites and animal manure are contributing to global warming and climate change. • Ozone depletion is caused by reactive chemicals (such as chlorofluorocarbons, CFCs) that react with and destroy the ozone layer in the atmosphere. This permits UV-B solar energy to reach Earth, putting all life at risk of mutations and other forms of damage. Water • The availability of water decreases as the human population rises. • Dam construction has advantages for humans but disadvantages for ecosystems. • Wetland destruction has a negative impact on water availability and quality. • Many modern agricultural practices are detrimental to the water cycle. Much water is wasted by inefficient irrigation systems used in agriculture. • Climate change is causing more frequent extreme climatic events such as droughts and floods. • The quantity and quality of water stores in aquifers is threatened by boreholes, municipal landfills, mining and lack of waterborne sewerage in informal settlements. • The cost of water rises as the demand increases and availability decreases. • Industry, agriculture, mining and poor settlement infrastructure pollute and reduce the quality of water, causing waterborne diseases and eutrophication. • Pollutants that decrease water quality come from a wide range of human impacts. • Purification and recycling of water are essential to sustain this limited resource. • Aquatic invasive alien plants have a negative effect on water resources and are costly to eradicate.

Food security • Food production has increased faster than the human population has over the past 40 years, but the availability of food per head of population has decreased, particularly in the developing world. • Climate change in the form of frequent floods and droughts and changes to the timing of seasons decreases food security. • Poor farming practices negatively affect food security. • Alien plants affect food security by decreasing the amount of available agricultural land. • Genetic vigour of domestic crops requires back-crossing with wild ancestor strains but many of these ancestral species are threatened by habitat loss. • Genetically engineered foods may help to improve food security, but so far they have not had much impact. • Food waste is greatest in Westernised countries. Loss of biodiversity • The sixth mass extinction that is occurring now is a direct result of human impact. • Habitat destruction, which reduces biodiversity, is accelerated by human activities such as overgrazing, monoculture, mining, wetland destruction, deforestation, planting extensive exotic forests, destruction of grasslands and other biomes, expanding cities and golf courses, illegal trading of wildlife, over-exploitation of selected species, introducing invasive alien species and poaching. • Mining has serious adverse effects on land, water and air. • Poaching is potentially causing species to become extinct and is negatively affecting biodiversity. • Invasive alien plants (IAPs) are rapidly replacing indigenous species of plants, at the expense of South Africa’s biodiversity, water resources and soil fertility. • Indigenous knowledge systems can provide effective strategies for conserving biodiversity but can also perpetuate destructive myths and cultural practices that undermine biodiversity. • South Africa’s medicinal plants are in global demand and require careful management to avoid over-exploitation. Solid waste disposal • Human industry, technology, consumerism and irresponsibility result in an ever-increasing load of waste. • Waste and landfill sites have a serious impact on all parts of the environment and undermine the efficiency of ecological functions and services. • The management of most landfill sites in South Africa is very costly and highly inefficient in terms of energy and resource recovery. • The waste hierarchy outlines levels of efficiency in managing and saving energy and resources. • Landfill sites can be managed to generate biogas or electricity and in the process also reclaim grey water. • Methane from landfills can be used to generate electricity for households. • Nuclear waste disposal is still the major problem associated with nuclear power.